Rapid cooling through the glass transition transiently increases ductility of PGA/PLLA copolymers: a proposed mechanism and implications for devices.

Rapid cooling through the glass transition transiently increases ductility of PGA/PLLA copolymers: a proposed mechanism and implications for devices. Research Abstract Details 

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Rapid cooling through the glass transition transiently increases ductility of PGA/PLLA copolymers: a proposed mechanism and implications for devices. Abstract Text:

William S Pietrzak,

Heating bioabsorbable plates above T(g) allows for temporary softening to facilitate adaptation to bone. This can, however, transiently alter the mechanical properties, a better understanding of which would provide further insight into the use of these polymers. Two types of unoriented L-lactide/glycolide copolymer wafer specimens (82:18 and 95:5 molar ratios) were heated to 90 degrees C, cooled at various rates, and mechanically tested (three-point bend). Long cooling times ( approximately 8 h) did not change mechanical properties compared to unheated controls, whereas faster cooling rates resulted in increased ductility (50-200% increase in energy to break and peak deformation), however, there was gradual recovery. Under simulated physiological incubation conditions (pH 7.4 buffer, 37 degrees C) partial recovery occurred within 48 h. These results fit well into the theoretical framework of free volume considerations. Following rapid cooling to below T(g), the polymer is not initially at equilibrium, containing excess free volume that contributes to increased molecular mobility and ductile behavior. As equilibrium is approached, free volume decreases and the material behaves as a glassy solid. While there is little clinical consequence as regards internal fixation devices, possible transient changes in permeability and other properties could have implications in drug delivery and other applications.

Rapid cooling through the glass transition transiently increases ductility of PGA/PLLA copolymers: a proposed mechanism and implications for devices. Publishing Authors By Initials

WS Pietrzak,

For similar natural sciences: physics: thermodynamics research abstracts see: natural sciences: physics: thermodynamics research

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Rapid cooling through the glass transition transiently increases ductility of PGA/PLLA copolymers: a proposed mechanism and implications for devices. Journal Published:

PUBLICATION TYPE: Journal Article

Journal: Journal of materials science. Materials in medicin

VOLUME: 18

Page Numbers: 1753-63

Journal Abbreviation:

ISSN: 0957-4530

DAY: 5

MONTH: 05

YEAR: 2007

Rapid cooling through the glass transition transiently increases ductility of PGA/PLLA copolymers: a proposed mechanism and implications for devices. Information

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LANGUAGE: eng

NlmUniqueID: 9013087

Rapid cooling through the glass transition transiently increases ductility of PGA/PLLA copolymers: a proposed mechanism and implications for devices. Keywords Mesh Terms:

KEYWORDS: Thermodynamics

MESH TERMS: chemistry

Chemical & Substance for Abstract: Rapid cooling through the glass transition transiently increases ductility of PGA/PLLA copolymers: a proposed mechanism and implications for devices. Information

Substance Name: Lactic Acid

Registry Number: 50-21-5

Grant and Affiliation Information for Rapid cooling through the glass transition transiently increases ductility of PGA/PLLA copolymers: a proposed mechanism and implications for devices.

AFFILIATION: Clinical Research, Biomet Inc, Warsaw, IN 46581, USA. bill.pietrzak@biometmail.com

Country: United States

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MEDLINETA: J Mater Sci Mater Med

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